Effects of sleep apnea syndrome on delayed memory and executive function in elderly adults.

OBJECTIVES: To identify differences in cognitive function between elderly adults with sleep apnea syndrome (SAS) and healthy controls. DESIGN: Cross-sectional. SETTING: Sleep laboratory at Seoul National University Bundang Hospital. PARTICIPANTS: Sixty-three elderly adults (26 female; mean age 68.2 ± 4.8) without cognitive disorders. MEASUREMENTS: Sleep-laboratory polysomnography findings and cognitive function results determined using the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Assessment Battery. RESULTS: When the control group (apnea-hypopnea index (AHI) < 15) was compared with the groups with mild to moderate (15 ≤ AHI < 30) and severe (AHI ≥ 30) SAS, significant differences in delayed recall (P = .003) and errors on the Trail-Making Test Part B (TMT B; P = .009) were observed, with participants with severe SAS showing greater impairment on both tests than controls (P = .02 and P = .01, respectively). Stepwise multiple regression showed that oxygen desaturation index (ß = -0.37, P = .003) and educational level (ß = 0.24, P = .04) determined delayed recall impairment (adjusted coefficient of determination (R (2)) = 17.8%, P = .003). TMT B errors were independently associated with educational level (ß = -0.41, P = .001) and AHI (ß = 0.31, P = .007; adjusted R (2) = 25.7%, P = .001). CONCLUSION: Severe SAS is associated with measures of delayed recall and executive function in cognitively healthy older adults. Although further study is needed, this evidence may provide further rationale for the treatment of SAS in older adults. Moreover, the role of SAS as a risk factor for cognitive disorders needs to be determined.

Effects of spaced retrieval training (SRT) on cognitive function in Alzheimer's disease (AD) patients.

Among the non-pharmacological treatments of dementia, SRT is a good candidate strategy for rehabilitating the cognition of AD patients. This study investigates the efficacy of SRT on the cognition of AD patients with very mild to mild disease. We administered 24-session SRT to 13 very mild and 6 mild AD patients. To assess the change of the neuropsychological performance after SRT, we performed the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease neuropsychological battery (CERAD-K), the logical memory test (LMT), the Benton visual retention test A (BVRT-A), and the digit span test (DST). All tests were administered both before and after SRT. Retention spans were significantly increased up to 24 min after SRT in both very mild and mild AD patients (p<0.05), and this improvement was maintained for different sets of target information. Retainable words were also significantly increased after SRT in the very mild AD patients (p=0.007). However, we observed no changes in neuropsychological performance after SRT. Although we did not observe improvements in the neuropsychological tests following SRT, our results suggest that the treatment was an effective intervention for improving the memory of very mild to mild AD patients, and could potentially improve learning and retention outside the training session.